It feels like a living universe, planets are varied and wild, the creatures are inventive, as are the vehicles, you can build bases, Terra from areas, plant crops etc, it’s a really relaxing game.
that said, of you love Elite for it's fantastic flight mechanics, you probably won't love No Man's Sky, at least not for the same reasons anyway.
This reminds me of the same confusion I had with Starbound: why do I have all these features that require me to settle down in one place to get the most from them when the game wants me to explore the far reaches of space? These things seem to pull in opposite directions.
Starbound at least lets you put a teleporter in your base so you can always return quickly no matter where in the universe you are.
There's no requirement to have a base of any sort. If you want to be purely nomadic with just a small ship, you can. But, bases are fun to build and design. Provides a solid income if you want it. From a psychological point of view, it's also nice to have a place to call home in the midst of a vast and nearly infinite universe.
It's a very flexible play structure.